Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
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FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_mbuf.c
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1 /* 2 * Copyright (c) 1982, 1986, 1988, 1991, 1993 3 * The Regents of the University of California. All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. All advertising materials mentioning features or use of this software 14 * must display the following acknowledgement: 15 * This product includes software developed by the University of 16 * California, Berkeley and its contributors. 17 * 4. Neither the name of the University nor the names of its contributors 18 * may be used to endorse or promote products derived from this software 19 * without specific prior written permission. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 * 33 * @(#)uipc_mbuf.c 8.2 (Berkeley) 1/4/94 34 * $FreeBSD: releng/5.1/sys/kern/uipc_mbuf.c 113490 2003-04-15 02:14:43Z silby $ 35 */ 36 37 #include "opt_mac.h" 38 #include "opt_param.h" 39 #include "opt_mbuf_stress_test.h" 40 41 #include <sys/param.h> 42 #include <sys/systm.h> 43 #include <sys/kernel.h> 44 #include <sys/lock.h> 45 #include <sys/mac.h> 46 #include <sys/malloc.h> 47 #include <sys/mbuf.h> 48 #include <sys/sysctl.h> 49 #include <sys/domain.h> 50 #include <sys/protosw.h> 51 52 int max_linkhdr; 53 int max_protohdr; 54 int max_hdr; 55 int max_datalen; 56 int m_defragpackets; 57 int m_defragbytes; 58 int m_defraguseless; 59 int m_defragfailure; 60 #ifdef MBUF_STRESS_TEST 61 int m_defragrandomfailures; 62 #endif 63 64 /* 65 * sysctl(8) exported objects 66 */ 67 SYSCTL_DECL(_kern_ipc); 68 SYSCTL_INT(_kern_ipc, KIPC_MAX_LINKHDR, max_linkhdr, CTLFLAG_RW, 69 &max_linkhdr, 0, ""); 70 SYSCTL_INT(_kern_ipc, KIPC_MAX_PROTOHDR, max_protohdr, CTLFLAG_RW, 71 &max_protohdr, 0, ""); 72 SYSCTL_INT(_kern_ipc, KIPC_MAX_HDR, max_hdr, CTLFLAG_RW, &max_hdr, 0, ""); 73 SYSCTL_INT(_kern_ipc, KIPC_MAX_DATALEN, max_datalen, CTLFLAG_RW, 74 &max_datalen, 0, ""); 75 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragpackets, CTLFLAG_RD, 76 &m_defragpackets, 0, ""); 77 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragbytes, CTLFLAG_RD, 78 &m_defragbytes, 0, ""); 79 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defraguseless, CTLFLAG_RD, 80 &m_defraguseless, 0, ""); 81 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragfailure, CTLFLAG_RD, 82 &m_defragfailure, 0, ""); 83 #ifdef MBUF_STRESS_TEST 84 SYSCTL_INT(_kern_ipc, OID_AUTO, m_defragrandomfailures, CTLFLAG_RW, 85 &m_defragrandomfailures, 0, ""); 86 #endif 87 88 /* 89 * "Move" mbuf pkthdr from "from" to "to". 90 * "from" must have M_PKTHDR set, and "to" must be empty. 91 */ 92 void 93 m_move_pkthdr(struct mbuf *to, struct mbuf *from) 94 { 95 96 #if 0 97 /* see below for why these are not enabled */ 98 M_ASSERTPKTHDR(to); 99 /* Note: with MAC, this may not be a good assertion. */ 100 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), 101 ("m_move_pkthdr: to has tags")); 102 #endif 103 KASSERT((to->m_flags & M_EXT) == 0, ("m_move_pkthdr: to has cluster")); 104 #ifdef MAC 105 /* 106 * XXXMAC: It could be this should also occur for non-MAC? 107 */ 108 if (to->m_flags & M_PKTHDR) 109 m_tag_delete_chain(to, NULL); 110 #endif 111 to->m_flags = from->m_flags & M_COPYFLAGS; 112 to->m_data = to->m_pktdat; 113 to->m_pkthdr = from->m_pkthdr; /* especially tags */ 114 SLIST_INIT(&from->m_pkthdr.tags); /* purge tags from src */ 115 from->m_flags &= ~M_PKTHDR; 116 } 117 118 /* 119 * Duplicate "from"'s mbuf pkthdr in "to". 120 * "from" must have M_PKTHDR set, and "to" must be empty. 121 * In particular, this does a deep copy of the packet tags. 122 */ 123 int 124 m_dup_pkthdr(struct mbuf *to, struct mbuf *from, int how) 125 { 126 127 #if 0 128 /* 129 * The mbuf allocator only initializes the pkthdr 130 * when the mbuf is allocated with MGETHDR. Many users 131 * (e.g. m_copy*, m_prepend) use MGET and then 132 * smash the pkthdr as needed causing these 133 * assertions to trip. For now just disable them. 134 */ 135 M_ASSERTPKTHDR(to); 136 /* Note: with MAC, this may not be a good assertion. */ 137 KASSERT(SLIST_EMPTY(&to->m_pkthdr.tags), ("m_dup_pkthdr: to has tags")); 138 #endif 139 #ifdef MAC 140 if (to->m_flags & M_PKTHDR) 141 m_tag_delete_chain(to, NULL); 142 #endif 143 to->m_flags = (from->m_flags & M_COPYFLAGS) | (to->m_flags & M_EXT); 144 if ((to->m_flags & M_EXT) == 0) 145 to->m_data = to->m_pktdat; 146 to->m_pkthdr = from->m_pkthdr; 147 SLIST_INIT(&to->m_pkthdr.tags); 148 return (m_tag_copy_chain(to, from, MBTOM(how))); 149 } 150 151 /* 152 * Lesser-used path for M_PREPEND: 153 * allocate new mbuf to prepend to chain, 154 * copy junk along. 155 */ 156 struct mbuf * 157 m_prepend(struct mbuf *m, int len, int how) 158 { 159 struct mbuf *mn; 160 161 MGET(mn, how, m->m_type); 162 if (mn == NULL) { 163 m_freem(m); 164 return (NULL); 165 } 166 if (m->m_flags & M_PKTHDR) 167 M_MOVE_PKTHDR(mn, m); 168 mn->m_next = m; 169 m = mn; 170 if (len < MHLEN) 171 MH_ALIGN(m, len); 172 m->m_len = len; 173 return (m); 174 } 175 176 /* 177 * Make a copy of an mbuf chain starting "off0" bytes from the beginning, 178 * continuing for "len" bytes. If len is M_COPYALL, copy to end of mbuf. 179 * The wait parameter is a choice of M_TRYWAIT/M_DONTWAIT from caller. 180 * Note that the copy is read-only, because clusters are not copied, 181 * only their reference counts are incremented. 182 */ 183 struct mbuf * 184 m_copym(struct mbuf *m, int off0, int len, int wait) 185 { 186 struct mbuf *n, **np; 187 int off = off0; 188 struct mbuf *top; 189 int copyhdr = 0; 190 191 KASSERT(off >= 0, ("m_copym, negative off %d", off)); 192 KASSERT(len >= 0, ("m_copym, negative len %d", len)); 193 if (off == 0 && m->m_flags & M_PKTHDR) 194 copyhdr = 1; 195 while (off > 0) { 196 KASSERT(m != NULL, ("m_copym, offset > size of mbuf chain")); 197 if (off < m->m_len) 198 break; 199 off -= m->m_len; 200 m = m->m_next; 201 } 202 np = ⊤ 203 top = 0; 204 while (len > 0) { 205 if (m == NULL) { 206 KASSERT(len == M_COPYALL, 207 ("m_copym, length > size of mbuf chain")); 208 break; 209 } 210 MGET(n, wait, m->m_type); 211 *np = n; 212 if (n == NULL) 213 goto nospace; 214 if (copyhdr) { 215 if (!m_dup_pkthdr(n, m, wait)) 216 goto nospace; 217 if (len == M_COPYALL) 218 n->m_pkthdr.len -= off0; 219 else 220 n->m_pkthdr.len = len; 221 copyhdr = 0; 222 } 223 n->m_len = min(len, m->m_len - off); 224 if (m->m_flags & M_EXT) { 225 n->m_data = m->m_data + off; 226 n->m_ext = m->m_ext; 227 n->m_flags |= M_EXT; 228 MEXT_ADD_REF(m); 229 } else 230 bcopy(mtod(m, caddr_t)+off, mtod(n, caddr_t), 231 (u_int)n->m_len); 232 if (len != M_COPYALL) 233 len -= n->m_len; 234 off = 0; 235 m = m->m_next; 236 np = &n->m_next; 237 } 238 if (top == NULL) 239 mbstat.m_mcfail++; /* XXX: No consistency. */ 240 241 return (top); 242 nospace: 243 m_freem(top); 244 mbstat.m_mcfail++; /* XXX: No consistency. */ 245 return (NULL); 246 } 247 248 /* 249 * Copy an entire packet, including header (which must be present). 250 * An optimization of the common case `m_copym(m, 0, M_COPYALL, how)'. 251 * Note that the copy is read-only, because clusters are not copied, 252 * only their reference counts are incremented. 253 * Preserve alignment of the first mbuf so if the creator has left 254 * some room at the beginning (e.g. for inserting protocol headers) 255 * the copies still have the room available. 256 */ 257 struct mbuf * 258 m_copypacket(struct mbuf *m, int how) 259 { 260 struct mbuf *top, *n, *o; 261 262 MGET(n, how, m->m_type); 263 top = n; 264 if (n == NULL) 265 goto nospace; 266 267 if (!m_dup_pkthdr(n, m, how)) 268 goto nospace; 269 n->m_len = m->m_len; 270 if (m->m_flags & M_EXT) { 271 n->m_data = m->m_data; 272 n->m_ext = m->m_ext; 273 n->m_flags |= M_EXT; 274 MEXT_ADD_REF(m); 275 } else { 276 n->m_data = n->m_pktdat + (m->m_data - m->m_pktdat ); 277 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 278 } 279 280 m = m->m_next; 281 while (m) { 282 MGET(o, how, m->m_type); 283 if (o == NULL) 284 goto nospace; 285 286 n->m_next = o; 287 n = n->m_next; 288 289 n->m_len = m->m_len; 290 if (m->m_flags & M_EXT) { 291 n->m_data = m->m_data; 292 n->m_ext = m->m_ext; 293 n->m_flags |= M_EXT; 294 MEXT_ADD_REF(m); 295 } else { 296 bcopy(mtod(m, char *), mtod(n, char *), n->m_len); 297 } 298 299 m = m->m_next; 300 } 301 return top; 302 nospace: 303 m_freem(top); 304 mbstat.m_mcfail++; /* XXX: No consistency. */ 305 return (NULL); 306 } 307 308 /* 309 * Copy data from an mbuf chain starting "off" bytes from the beginning, 310 * continuing for "len" bytes, into the indicated buffer. 311 */ 312 void 313 m_copydata(const struct mbuf *m, int off, int len, caddr_t cp) 314 { 315 u_int count; 316 317 KASSERT(off >= 0, ("m_copydata, negative off %d", off)); 318 KASSERT(len >= 0, ("m_copydata, negative len %d", len)); 319 while (off > 0) { 320 KASSERT(m != NULL, ("m_copydata, offset > size of mbuf chain")); 321 if (off < m->m_len) 322 break; 323 off -= m->m_len; 324 m = m->m_next; 325 } 326 while (len > 0) { 327 KASSERT(m != NULL, ("m_copydata, length > size of mbuf chain")); 328 count = min(m->m_len - off, len); 329 bcopy(mtod(m, caddr_t) + off, cp, count); 330 len -= count; 331 cp += count; 332 off = 0; 333 m = m->m_next; 334 } 335 } 336 337 /* 338 * Copy a packet header mbuf chain into a completely new chain, including 339 * copying any mbuf clusters. Use this instead of m_copypacket() when 340 * you need a writable copy of an mbuf chain. 341 */ 342 struct mbuf * 343 m_dup(struct mbuf *m, int how) 344 { 345 struct mbuf **p, *top = NULL; 346 int remain, moff, nsize; 347 348 /* Sanity check */ 349 if (m == NULL) 350 return (NULL); 351 M_ASSERTPKTHDR(m); 352 353 /* While there's more data, get a new mbuf, tack it on, and fill it */ 354 remain = m->m_pkthdr.len; 355 moff = 0; 356 p = ⊤ 357 while (remain > 0 || top == NULL) { /* allow m->m_pkthdr.len == 0 */ 358 struct mbuf *n; 359 360 /* Get the next new mbuf */ 361 MGET(n, how, m->m_type); 362 if (n == NULL) 363 goto nospace; 364 if (top == NULL) { /* first one, must be PKTHDR */ 365 if (!m_dup_pkthdr(n, m, how)) 366 goto nospace; 367 nsize = MHLEN; 368 } else /* not the first one */ 369 nsize = MLEN; 370 if (remain >= MINCLSIZE) { 371 MCLGET(n, how); 372 if ((n->m_flags & M_EXT) == 0) { 373 (void)m_free(n); 374 goto nospace; 375 } 376 nsize = MCLBYTES; 377 } 378 n->m_len = 0; 379 380 /* Link it into the new chain */ 381 *p = n; 382 p = &n->m_next; 383 384 /* Copy data from original mbuf(s) into new mbuf */ 385 while (n->m_len < nsize && m != NULL) { 386 int chunk = min(nsize - n->m_len, m->m_len - moff); 387 388 bcopy(m->m_data + moff, n->m_data + n->m_len, chunk); 389 moff += chunk; 390 n->m_len += chunk; 391 remain -= chunk; 392 if (moff == m->m_len) { 393 m = m->m_next; 394 moff = 0; 395 } 396 } 397 398 /* Check correct total mbuf length */ 399 KASSERT((remain > 0 && m != NULL) || (remain == 0 && m == NULL), 400 ("%s: bogus m_pkthdr.len", __func__)); 401 } 402 return (top); 403 404 nospace: 405 m_freem(top); 406 mbstat.m_mcfail++; /* XXX: No consistency. */ 407 return (NULL); 408 } 409 410 /* 411 * Concatenate mbuf chain n to m. 412 * Both chains must be of the same type (e.g. MT_DATA). 413 * Any m_pkthdr is not updated. 414 */ 415 void 416 m_cat(struct mbuf *m, struct mbuf *n) 417 { 418 while (m->m_next) 419 m = m->m_next; 420 while (n) { 421 if (m->m_flags & M_EXT || 422 m->m_data + m->m_len + n->m_len >= &m->m_dat[MLEN]) { 423 /* just join the two chains */ 424 m->m_next = n; 425 return; 426 } 427 /* splat the data from one into the other */ 428 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 429 (u_int)n->m_len); 430 m->m_len += n->m_len; 431 n = m_free(n); 432 } 433 } 434 435 void 436 m_adj(struct mbuf *mp, int req_len) 437 { 438 int len = req_len; 439 struct mbuf *m; 440 int count; 441 442 if ((m = mp) == NULL) 443 return; 444 if (len >= 0) { 445 /* 446 * Trim from head. 447 */ 448 while (m != NULL && len > 0) { 449 if (m->m_len <= len) { 450 len -= m->m_len; 451 m->m_len = 0; 452 m = m->m_next; 453 } else { 454 m->m_len -= len; 455 m->m_data += len; 456 len = 0; 457 } 458 } 459 m = mp; 460 if (mp->m_flags & M_PKTHDR) 461 m->m_pkthdr.len -= (req_len - len); 462 } else { 463 /* 464 * Trim from tail. Scan the mbuf chain, 465 * calculating its length and finding the last mbuf. 466 * If the adjustment only affects this mbuf, then just 467 * adjust and return. Otherwise, rescan and truncate 468 * after the remaining size. 469 */ 470 len = -len; 471 count = 0; 472 for (;;) { 473 count += m->m_len; 474 if (m->m_next == (struct mbuf *)0) 475 break; 476 m = m->m_next; 477 } 478 if (m->m_len >= len) { 479 m->m_len -= len; 480 if (mp->m_flags & M_PKTHDR) 481 mp->m_pkthdr.len -= len; 482 return; 483 } 484 count -= len; 485 if (count < 0) 486 count = 0; 487 /* 488 * Correct length for chain is "count". 489 * Find the mbuf with last data, adjust its length, 490 * and toss data from remaining mbufs on chain. 491 */ 492 m = mp; 493 if (m->m_flags & M_PKTHDR) 494 m->m_pkthdr.len = count; 495 for (; m; m = m->m_next) { 496 if (m->m_len >= count) { 497 m->m_len = count; 498 break; 499 } 500 count -= m->m_len; 501 } 502 while (m->m_next) 503 (m = m->m_next) ->m_len = 0; 504 } 505 } 506 507 /* 508 * Rearange an mbuf chain so that len bytes are contiguous 509 * and in the data area of an mbuf (so that mtod and dtom 510 * will work for a structure of size len). Returns the resulting 511 * mbuf chain on success, frees it and returns null on failure. 512 * If there is room, it will add up to max_protohdr-len extra bytes to the 513 * contiguous region in an attempt to avoid being called next time. 514 */ 515 struct mbuf * 516 m_pullup(struct mbuf *n, int len) 517 { 518 struct mbuf *m; 519 int count; 520 int space; 521 522 /* 523 * If first mbuf has no cluster, and has room for len bytes 524 * without shifting current data, pullup into it, 525 * otherwise allocate a new mbuf to prepend to the chain. 526 */ 527 if ((n->m_flags & M_EXT) == 0 && 528 n->m_data + len < &n->m_dat[MLEN] && n->m_next) { 529 if (n->m_len >= len) 530 return (n); 531 m = n; 532 n = n->m_next; 533 len -= m->m_len; 534 } else { 535 if (len > MHLEN) 536 goto bad; 537 MGET(m, M_DONTWAIT, n->m_type); 538 if (m == NULL) 539 goto bad; 540 m->m_len = 0; 541 if (n->m_flags & M_PKTHDR) 542 M_MOVE_PKTHDR(m, n); 543 } 544 space = &m->m_dat[MLEN] - (m->m_data + m->m_len); 545 do { 546 count = min(min(max(len, max_protohdr), space), n->m_len); 547 bcopy(mtod(n, caddr_t), mtod(m, caddr_t) + m->m_len, 548 (u_int)count); 549 len -= count; 550 m->m_len += count; 551 n->m_len -= count; 552 space -= count; 553 if (n->m_len) 554 n->m_data += count; 555 else 556 n = m_free(n); 557 } while (len > 0 && n); 558 if (len > 0) { 559 (void) m_free(m); 560 goto bad; 561 } 562 m->m_next = n; 563 return (m); 564 bad: 565 m_freem(n); 566 mbstat.m_mpfail++; /* XXX: No consistency. */ 567 return (NULL); 568 } 569 570 /* 571 * Partition an mbuf chain in two pieces, returning the tail -- 572 * all but the first len0 bytes. In case of failure, it returns NULL and 573 * attempts to restore the chain to its original state. 574 * 575 * Note that the resulting mbufs might be read-only, because the new 576 * mbuf can end up sharing an mbuf cluster with the original mbuf if 577 * the "breaking point" happens to lie within a cluster mbuf. Use the 578 * M_WRITABLE() macro to check for this case. 579 */ 580 struct mbuf * 581 m_split(struct mbuf *m0, int len0, int wait) 582 { 583 struct mbuf *m, *n; 584 u_int len = len0, remain; 585 586 for (m = m0; m && len > m->m_len; m = m->m_next) 587 len -= m->m_len; 588 if (m == NULL) 589 return (NULL); 590 remain = m->m_len - len; 591 if (m0->m_flags & M_PKTHDR) { 592 MGETHDR(n, wait, m0->m_type); 593 if (n == NULL) 594 return (NULL); 595 n->m_pkthdr.rcvif = m0->m_pkthdr.rcvif; 596 n->m_pkthdr.len = m0->m_pkthdr.len - len0; 597 m0->m_pkthdr.len = len0; 598 if (m->m_flags & M_EXT) 599 goto extpacket; 600 if (remain > MHLEN) { 601 /* m can't be the lead packet */ 602 MH_ALIGN(n, 0); 603 n->m_next = m_split(m, len, wait); 604 if (n->m_next == NULL) { 605 (void) m_free(n); 606 return (NULL); 607 } else { 608 n->m_len = 0; 609 return (n); 610 } 611 } else 612 MH_ALIGN(n, remain); 613 } else if (remain == 0) { 614 n = m->m_next; 615 m->m_next = NULL; 616 return (n); 617 } else { 618 MGET(n, wait, m->m_type); 619 if (n == NULL) 620 return (NULL); 621 M_ALIGN(n, remain); 622 } 623 extpacket: 624 if (m->m_flags & M_EXT) { 625 n->m_flags |= M_EXT; 626 n->m_ext = m->m_ext; 627 MEXT_ADD_REF(m); 628 n->m_data = m->m_data + len; 629 } else { 630 bcopy(mtod(m, caddr_t) + len, mtod(n, caddr_t), remain); 631 } 632 n->m_len = remain; 633 m->m_len = len; 634 n->m_next = m->m_next; 635 m->m_next = NULL; 636 return (n); 637 } 638 /* 639 * Routine to copy from device local memory into mbufs. 640 * Note that `off' argument is offset into first mbuf of target chain from 641 * which to begin copying the data to. 642 */ 643 struct mbuf * 644 m_devget(char *buf, int totlen, int off, struct ifnet *ifp, 645 void (*copy)(char *from, caddr_t to, u_int len)) 646 { 647 struct mbuf *m; 648 struct mbuf *top = 0, **mp = ⊤ 649 int len; 650 651 if (off < 0 || off > MHLEN) 652 return (NULL); 653 654 MGETHDR(m, M_DONTWAIT, MT_DATA); 655 if (m == NULL) 656 return (NULL); 657 m->m_pkthdr.rcvif = ifp; 658 m->m_pkthdr.len = totlen; 659 len = MHLEN; 660 661 while (totlen > 0) { 662 if (top) { 663 MGET(m, M_DONTWAIT, MT_DATA); 664 if (m == NULL) { 665 m_freem(top); 666 return (NULL); 667 } 668 len = MLEN; 669 } 670 if (totlen + off >= MINCLSIZE) { 671 MCLGET(m, M_DONTWAIT); 672 if (m->m_flags & M_EXT) 673 len = MCLBYTES; 674 } else { 675 /* 676 * Place initial small packet/header at end of mbuf. 677 */ 678 if (top == NULL && totlen + off + max_linkhdr <= len) { 679 m->m_data += max_linkhdr; 680 len -= max_linkhdr; 681 } 682 } 683 if (off) { 684 m->m_data += off; 685 len -= off; 686 off = 0; 687 } 688 m->m_len = len = min(totlen, len); 689 if (copy) 690 copy(buf, mtod(m, caddr_t), (u_int)len); 691 else 692 bcopy(buf, mtod(m, caddr_t), (u_int)len); 693 buf += len; 694 *mp = m; 695 mp = &m->m_next; 696 totlen -= len; 697 } 698 return (top); 699 } 700 701 /* 702 * Copy data from a buffer back into the indicated mbuf chain, 703 * starting "off" bytes from the beginning, extending the mbuf 704 * chain if necessary. 705 */ 706 void 707 m_copyback(struct mbuf *m0, int off, int len, caddr_t cp) 708 { 709 int mlen; 710 struct mbuf *m = m0, *n; 711 int totlen = 0; 712 713 if (m0 == NULL) 714 return; 715 while (off > (mlen = m->m_len)) { 716 off -= mlen; 717 totlen += mlen; 718 if (m->m_next == NULL) { 719 n = m_get_clrd(M_DONTWAIT, m->m_type); 720 if (n == NULL) 721 goto out; 722 n->m_len = min(MLEN, len + off); 723 m->m_next = n; 724 } 725 m = m->m_next; 726 } 727 while (len > 0) { 728 mlen = min (m->m_len - off, len); 729 bcopy(cp, off + mtod(m, caddr_t), (u_int)mlen); 730 cp += mlen; 731 len -= mlen; 732 mlen += off; 733 off = 0; 734 totlen += mlen; 735 if (len == 0) 736 break; 737 if (m->m_next == NULL) { 738 n = m_get(M_DONTWAIT, m->m_type); 739 if (n == NULL) 740 break; 741 n->m_len = min(MLEN, len); 742 m->m_next = n; 743 } 744 m = m->m_next; 745 } 746 out: if (((m = m0)->m_flags & M_PKTHDR) && (m->m_pkthdr.len < totlen)) 747 m->m_pkthdr.len = totlen; 748 } 749 750 void 751 m_print(const struct mbuf *m) 752 { 753 int len; 754 const struct mbuf *m2; 755 756 len = m->m_pkthdr.len; 757 m2 = m; 758 while (len) { 759 printf("%p %*D\n", m2, m2->m_len, (u_char *)m2->m_data, "-"); 760 len -= m2->m_len; 761 m2 = m2->m_next; 762 } 763 return; 764 } 765 766 u_int 767 m_fixhdr(struct mbuf *m0) 768 { 769 u_int len; 770 771 len = m_length(m0, NULL); 772 m0->m_pkthdr.len = len; 773 return (len); 774 } 775 776 u_int 777 m_length(struct mbuf *m0, struct mbuf **last) 778 { 779 struct mbuf *m; 780 u_int len; 781 782 len = 0; 783 for (m = m0; m != NULL; m = m->m_next) { 784 len += m->m_len; 785 if (m->m_next == NULL) 786 break; 787 } 788 if (last != NULL) 789 *last = m; 790 return (len); 791 } 792 793 /* 794 * Defragment a mbuf chain, returning the shortest possible 795 * chain of mbufs and clusters. If allocation fails and 796 * this cannot be completed, NULL will be returned, but 797 * the passed in chain will be unchanged. Upon success, 798 * the original chain will be freed, and the new chain 799 * will be returned. 800 * 801 * If a non-packet header is passed in, the original 802 * mbuf (chain?) will be returned unharmed. 803 */ 804 struct mbuf * 805 m_defrag(struct mbuf *m0, int how) 806 { 807 struct mbuf *m_new = NULL, *m_final = NULL; 808 int progress = 0, length; 809 810 if (!(m0->m_flags & M_PKTHDR)) 811 return (m0); 812 813 #ifdef MBUF_STRESS_TEST 814 if (m_defragrandomfailures) { 815 int temp = arc4random() & 0xff; 816 if (temp == 0xba) 817 goto nospace; 818 } 819 #endif 820 821 if (m0->m_pkthdr.len > MHLEN) 822 m_final = m_getcl(how, MT_DATA, M_PKTHDR); 823 else 824 m_final = m_gethdr(how, MT_DATA); 825 826 if (m_final == NULL) 827 goto nospace; 828 829 if (m_dup_pkthdr(m_final, m0, how) == NULL) 830 goto nospace; 831 832 m_new = m_final; 833 834 while (progress < m0->m_pkthdr.len) { 835 length = m0->m_pkthdr.len - progress; 836 if (length > MCLBYTES) 837 length = MCLBYTES; 838 839 if (m_new == NULL) { 840 if (length > MLEN) 841 m_new = m_getcl(how, MT_DATA, 0); 842 else 843 m_new = m_get(how, MT_DATA); 844 if (m_new == NULL) 845 goto nospace; 846 } 847 848 m_copydata(m0, progress, length, mtod(m_new, caddr_t)); 849 progress += length; 850 m_new->m_len = length; 851 if (m_new != m_final) 852 m_cat(m_final, m_new); 853 m_new = NULL; 854 } 855 if (m0->m_next == NULL) 856 m_defraguseless++; 857 m_freem(m0); 858 m0 = m_final; 859 m_defragpackets++; 860 m_defragbytes += m0->m_pkthdr.len; 861 return (m0); 862 nospace: 863 m_defragfailure++; 864 if (m_new) 865 m_free(m_new); 866 if (m_final) 867 m_freem(m_final); 868 return (NULL); 869 }
Cache object: baee1defb862228276ebf228efa43a4d
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